Dye transfer control by silver ions



May 13, 196;)

DYE TRANSFER CONTROL BY Filed July 24, 1

** ZMM/QMZQ/ H. G. ROGERS SILVER IONS VSUPPORT -COLOR-PROVIDING MATERIAL SILVER HALIDE EMULSION nocessme cowosmou RECEIVING LAYER SUPPORT FIG.I

SUPPORT SILVER HALIDE EMULSION PROCE SSING COMPOSITION "COLOR-PROVIDING MATERIAL SUPPORT FIG. 2

INVENTOR. flown/d 61. Kay

@Uufim elm ATTORNEYS 5M and United States Patent O 3,443,941 DYE TRANSFER CONTROL BY SILVER IONS Howard G. Rogers, Weston, Mass., assignor to Polaroid Corporation, Cambridge, Mass, a corporation of Delaware Filed July 24, 1967, Ser. No. 655,502 Int. Cl. G03c 7/00, /54 US. Cl. 96-3 21 Claims ABSTRACT OF THE DISCLOSURE This application relates to color photography and it discloses photographic systems wherein silver ions formed as a function of development of an exposed light-sensitive silver halide emulsion are utilized to control transfer of a color-providing substance to a stratum to form a color transfer image thereon.

BACKGROUND OF THE INVENTION It has heretofore been known to prepare color transfer images by various processes wherein the differential between exhausted and unexhausted developing agent is utilized to control transfer of a color-providing substance, e.g., a complete dye, to a stratum to form a color image thereon. For example, it has heretofore been suggested to control the availability for diffusion of a color-providing substance by unexhausted developing agent which reduces an immobile or non-diffusible substance to render it diffusible. Processes of this nature are disclosed, for example, in US. Patent No. 3,185,567 issued to Howard G. Rogers.

In the preparation of silver transfer images in accordance with diffusion transfer processes such as are disclosed in US. Patent No. 2,543,181 issued to Edwin H. Land, an exposed photosensitive element comprising a light-sensitive silver halide emulsion is developed by applying to the emulsion a processing composition comprising an aqueous alkaline solution of a silver halide developing agent and a silver halide solvent. In exposed areas, the silver halide is reduced to image silver while in unexposed areas an imagewise distribution of a soluble silver complex is formed. This imagewise distribution of soluble silver complex is at least in part transferred, by imbibition, to a superposed image-receiving layer where it is reduced to image silver to provide thereon a positive silver transfer image.

SUMMARY OF THE INVENTION The present invention in effect borrows certain principles from the silver diffusion transfer art for preparing black and white prints and utilizes the properties of the imagewise distribution of silver ions in the soluble silver complex to control imagewise transfer of a color-providing substance to a stratum to form a color image thereon. Included within the class of color-providing materials contemplated for use in this invention are normally diffusible color-providing materials which are rendered non-diffusible upon reaction with silver ions and/ or the soluble silver complex containing the same, and normally non-diffusible color-providing materials which are rendered diffusible upon reaction with silver ions and/or the soluble silver complex containing the same. These color-providing materials may be complete dyes or dye intermediates, i.e., materials which form a complete dye upon subsequent reaction as, for example, coupling during or following transfer. Such color-providing materials exclude and hence are distinguishable from silver halide developers, e.g. color developers, which upon oxidation react with a coupler to provide a complete dye.

BRIEF DESCRIPTION OF THE DRAWING FIGURE 1 is an enlarged, diagrammatic, fragmentary sectional view illustrating the preparation of a color image according to one aspect of this invention; and

'ice

FIG. 2 is a similar view illustrating another aspect of the invention.

PREFERRED EMBODIMENT In a preferred embodiment the color-providing material comprises a complete dye containing a moiety which is known in the photographic art as an organic antifogging agent. It has been found quite unexpectedly that this moiety reacts with the silver ions, for example, by forming addition complexes, to provide a relatively stable, non-diffusible, silver containing reaction product. When such a compound is placed in a layer in the photosensitive element, e.g., between the silver halide emulsion and a support therefor, upon development of the exposed photosensitive element with a processing composition including a silver halide solvent, silver ions formed as a function of development migrate to the layer containing the compound to render it non-diffusible in terms of unexposed areas of the emulsion layer, so that an imagewise distribution of diffusible dye remains in terms of exposed areas of the emulsion. This latter imagewise distribution may then be transferred at least in part by imbibition to a superposed stratum to impart a negative color transfer image thereon.

As was mentioned previously this application relates to color photography and, more particularly, to novel systems for preparing color images wherein silver ions formed as a function of development are utilized to control transfer of a color-providing substance.

A primary object of this invention, therefore, is to provi-de novel photographic systems for preparing color images.

Another object is to provide novel products and processes for preparing novel color transfer images.

Still another object is to provide novel systems wherein a light-sensitive silver halide emulsion is exposed, developed and silver ions formed as a function of development are utilized to control transfer of a color-providing substance to a stratum to form a color transfer image thereon.

These and other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the several steps and the relation and order of one or more of such steps with respect to each of the others, and the product possessing the features, properties and the relation of elements which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawing.

In one embodiment of this invention, negative color transfer images are obtained by means of rendering immobile or non-diffusible by the imagewise distribution of silver ions a normally mobile or dilfusible color-providing material, thereby providing an imagewise distribution of mobile or diffusible color-providing material in terms of exposed areas, and transferring this latter imagewise distribution, at least in part, to a stratum to form a negative color transfer image. This may be accomplished by applying to a photosensitive element comprising an exposed silver halide emulsion and a layer of the color-providing material a processing composition comprising an aqueous alkaline solution of a silver halide developing agent, and a silver halide solvent. In known manner, an imagewise distribution of a soluble silver complex is formed in terms of unexposed areas. This soluble silver complex migrates to the color-providing material where the silver ions contained in the complex react with the color-providing material to render it relatively non-diffusing. This reaction may, for example, be a complexing by the silver ions or an oxidation reaction to provide a less mobile product. In any event, the reaction provides an imagewise distribution of more mobile and diffusible color-providing material in terms of exposed areas of the silver halide emulsion and this imagewise distribution is transferred at least in part, by irnbibition, to a superposed dyeable stratum to form a negative color image thereon. It will be appreciated that if at least a substantial portion of this imagewise distribution is so transferred or otherwise removed, a positive color image will remain in the photo sensitive layer. If desired, the photosensitive element may contain a transparent support and the resulting positive image may be viewable by reflected light through this support which serves additionally to protect the image from abrasion and degradative changes. To this end, one or more layers may be provided in the photosensitive element to mask effectively the silver image also contained therein by development and to provide a requisite background for viewing the color image. This layer may, for example, contain a white pigment or other material such as titanium dioxide. A positive image may also be obtained in the photosensitive element by bleaching: and fixing the silver. Any visible amounts of color-providing material remaining in the highlight areas may be removed, if desired, by procedures known in the art.

From the foregoing description it will be apparent that the term mobile, ditfusible or soluble as used throughout the specification and appended claims in the description of the color-providing material denotes the property of the material to be mobile, diflusible or soluble at least in the processing composition employed. In like manner, it will also be apparent that the term immobile, non-ditfusible or insoluble, denotes the property of the material to be so at least in the processing composition employed.

As was mentioned previously, the processing composition comprises essentially an aqueous alkaline solution of a silver halide solvent and a silver halide developing agent. The named ingredients may be present initially in the aqueous medium or any of them may be present initially elsewhere in the photographic product, as heretofore suggested in the art, in which case the processing composition is formed by contacting the product with the aqueous medium and forming a solution of the necessary ingredients therein.

The alkaline material employed may be any of those heretofore employed, e.g., sodium or potassium hydroxide, etc., and the silver halide solvent may also be any of the heretofore known materials, e.g., sodium or potassium thiosulfate, etc. The selection of these materials is not critical to the practice of this invention.

The silver halide developing agent also comprises one of those heretofore known in the art. However, it has been found that in certain instances, dihydroxybenzene developers such as hydroquinone and its derivatives tend to form as a function of development oxidation products which may react with the color-providing material in a manner adverse to the system upon which color transfer image formation is here predicated. This is true in the case of the compounds containing an antifogging moiety which are described with particularity hereinafter. Thus, it has been found, quite unexpectedly, that many antifogfants will react with oxidized dihydroxybenzene developers to form a reaction product which is less mobile and diffusible. In such cases it may be necessary to employ a developer which will not so react either in its reduced or oxidized form in such a manner as to interfere with the reaction mechanism upon which image formation is predicated. As examples of such useful developers, mention may be made of the known classes of diaminobenzene and aminophenol developers, including substituted derivatives thereof. The selection of the particular developer and instances where a. dihydroxybenzene developer should be avoided will be readily apparent to those skilled in the art in the light of this description.

The color-providing material may be present initially in the photosensitive element in a layer other than the .4 layer containing the light-sensitive silver halide emulsion, e.g., in a layer between the support and the emulsion layer, or it may also 'be present in the photosensitive layer itself, assuming of course that this material is photo graphically innocuous, i.e., does not adversely affect or impair image formation at least to any appreciable extent, or, if not photographically innocuous itself, the material is present in such a manner as not so to affect adversely the light-sensitive emulsion, e.g., is rendered photographically innocuous by appropriate means. Preferably, the color-providing material is contained in a separate layer and one or more spacer layers may be provided between this layer and the silver halide emulsion layer.

FIGURE 1 illustrates the processing of a photosensitive element of the foregoing description to prepare a color transfer image. As shown therein, an exposed photosensitive elemen-t including a support 10, a layer of colorproviding material 11 and a light-sensitive silver halide emulsion layer 12 is placed in superposition with an image-receiving element comprising a receiving layer, e.g., a dyeable stratum 13 and a support 14 therefor; and while the two elements are in superposition, a processing composition 15 is spread therebetween.

Processing composition 15, or any of the ingredients thereof, may, if desired, be confined initially in a frangible container such as disclosed in US. Patent No. 2,543,181, the container being positioned in the film unit so as to be capable upon rupturing of spreading its contents in a substantially uniform layer between the superposed layers. It will be appreciated that the respective elements may be placed in superposition following impregnation with the processing composition according to procedures known in the art.

The film structure shown in FIGURE 1 may be varied, for example, in the manner heretofore suggested, and it is intended to be illustrative only of one product structure useful in the preparation of color transfer images according to the present invention.

One particularly useful class of norm-ally diifusible color-providing materials comprises complete dyes containing a substituent or moiety which is reactable with the silver ions and/or the soluble silver complex containing the same to render the dye-containing reaction product non-ditfusible in the processing fluid. Included within this class of compounds are those complete dyes containing a moiety which is known in the photographic art as an organic antifogging agent. It has been found, quite unexpectedly, that this moiety reacts with the silver ions, for example by forming addition complexes, to provide a relatively stable, non-ditfusible silver-containing reaction product. As examples of such anti-foggant moieties, mention may be made of benzimidazoles, thiooarbazones, benzotriazoles, mercaptothiazoles, hyd-roxyquinolines, azolethiones, azopyridines, bis-pyraz-oles, tetrazoindenes, etc.

Such compounds may be defined as dyes which are dilfusible in an aqueous alkaline medium and which may be represented by the following formula:

(A) D-A wherein A is a substituent reactable with silver ions to provide a reaction product which is non-ditfusible in the said aqueous alkaline medium, e.g., a monovalent radical of an organic antifogging agent, and D is the remainder of the dye molecule.

As examples of compounds within Formula A which are contemplated as useful in this embodiment of the invention, mention may 'be made of the following:

EN N =N (7) 0 EN N =on B Hz)zCOOH zHs fir .Cr OOOH HO \N/OH 2 15) Ho NH:

IT- N=N N= |N o sso J LN/ 1! I \N N N\ i H U011; U011, H

0 NHCH2CH2 N l /N NH-CHaCH2- 18 s OaN Ts];

19 /N\[SH \N/ SH o11, s s

It will be noted from the foregoing illustrative compounds, that it is Within the scope of this invention to employ metal complexed dyes. The dyes, that is, noncomplexed dyes, may also be complexed during or subsequent to image formation in a manner to be described hereinafter.

The following examples show by way of illustration and not by way of limitation this embodiment of the invention wherein a negative color transfer image is formed.

EXAMPLE I On a cellulose acetate support overcoated with a layer containing 200 mg. per square foot of gelatin was coated at room temperature at a rate of ten feet per minute a solution containing 95.0 cc. of acetone; 5.0 cc. of dimethyl formamide; 2.0 g. of cellulose acetate hydrogen phthalate, and 1.0 g. of the dye designated by Formula 1. On top of the resulting layer was coated a first layer of gelatin and a second layer of cellulose acetate hydrogen phthalate. Finally, a light-sensitive silver iodobromide emulsion layer was applied to provide a photosensitive element. This photosensitive element was exposed for one one-hundredth of a second to blue light through a density step tablet and the thus exposed element was developed by spreading between this element and a superposed image-receiving element containing a dyeable stratum at a gap of .0042" a processing composition comprising the following proportions of ingredients:

Water cc 100.0 Hydroxy ethyl cellulose g 3.9 Sodium hydroxide g 5.0 p-Methylamino-phenol g 1.6 Sodium sulfite g 2.0 Sodium thiosulfate g 2.0 4-amino-2-methyl-6-methoxy-pheno1 g 0.5

The image-receiving element was prepared in accOnd-ance with the disclosure of the copending application of Edwin H. Land, Ser. No. 234,864, filed Nov. 1, 1962, now US. Patent No. 3,362,819, and comprised a layer of a 2:1 mixture by weight, of polyvinyl alcohol and poly-4-vinyl pyridine, a layer of polyvinyl alcohol, and a layer of a half-butyl ester of poly-(ethylene/maleic anhydride) coated on a baryta paper support. After an imbibition period of about 50 seconds, the image-receiving element was separated to reveal thereon a negative yellow image have a D of 1.73 and a D of 0.39.

EXAMPLE II On a cellulose acetate support overcoated with a layer of gelatin was coated at room temperature at a rate of ten feet per minute a solution containing 100.0 cc. of tetrahydrofuran, 2.0 g. of cellulose acetate hydrogen phthalate and 0.89 g. of the dye designated by Formula 2. On top of the resulting layer was coated a first layer of gelatin and a second layer of cellulose acetate hydrogen phthalate. Finally, a light-sensitive silver iodobromide emulsion layer was applied to provide a photosensitive element. This element was exposed for one one-hundredth of a second and the thus exposed element was developed by spreading between this element and a superposed image-receiving element (as in Example I) at a gap of .0038" a processing composition comprising the following proportions of ingredients:

Water cc 100.0

Hydroxy ethyl cellulose g 3.9 Sodium hydroxide g 5 .0 p-Methylamino-phenol g 1 .6 Sodium sulfite g 2.0 Sodium thiosulfate g 1.0 4-amino-2-methyl-fi-methoxy-phenol g 0.5

After an imbibition period of about 50 seconds, a negative orange image was obtained.

As was mentioned earlier, the color-providing material may be present initially in the photosensitive layer itself, assuming that it is photographically innocuous or, if not photographically innocuous itself, it is present in such a manner as not so to affect adversely the light-sensitive emulsion. This may be accomplished by including in the same layer a compound which deactivates the color-providing material prior to processing but which does not interfere with the development process upon which image formation is here predicated. By way of example, it is contemplated that a dye which is not normally photographically innocuous may be deactivated to render it so by appropriate reaction with a compound, e.g., a zirconium salt, which forms a relatively innocuous salt having a dissociation constant great enough to allow sufficient transfer during processing.

The following example is illustrative of this aspect of the invention:

EXAMPLE III A first photosensitive element was prepared by coating on a cellulose acetate support overcoated with 200 mg.

per square foot of gelatin, at 40 C. and at a rate of 10 feet per minute a coating containing 10 cc. of the dye mixture prepared in Example 1, 7.5 cc. of a silver iodobromide emulsion, 13.5 cc. of water and 4.0 cc. of saponin. A second photosensitive element was prepared in the same manner, except that the coating contained 9.0 cc. of the dye mixture, 1.0 cc. of 1% zirconium sulfate, 7.5 cc. of the same emulsion, 13.5 cc. of water and 4.0 cc. of saponin. Each photosensitive element was exposed and processed in the manner described in Example I to provide a yellow transfer image of satisfactory density and contrast. However, the second photosensitive element containing the zirconium sulfate showed at least two more steps of silver development than did the first one.

In the foregoing embodiment of the invention, a normally mobile or diffusible color-providing material is rendered non-diffusing by silver ions formed as a function of development to provide a negative color image.

In another embodiment of the invention, use is made of a normally immobile or non-diifusible color-providing material which is rendered mobile and diifusible by silver ions formed as a function of development so that an imagewise distribution of more ditiusible color-providing material in terms of unexposed areas may be transferred at least in part, by imbibition, to a dyeable stratum to form a positive color image thereon.

By way of illustration, such a color-providing material may comprise a compound having a diifusible or soluble color-providing moiety, e.g., a soluble dye moiety and an insolubilizing or anchoring moiety for rendering the compound non-diffusible. Image formation may be effected by separating the color-providing moiety from the anchoring moiety by reaction with the silver ions. Following separation, the resulting compound containing the color providing moiety is now free to transfer to the dyeable stratum to provide a positive color image thereon.

In one aspect of this embodiment, the anchoring" substituent is removed by reaction with silver ions, as, for example, by replacement or oxidation, to release the mobile and ditfusible color-providing moiety for transfer, by imbibition, to the d'yeable stratum to provide a positive color image thereon. In this aspect, the imagewise distribution of soluble silver complex in terms of unexposed and partially exposed areas contacts the compound containing the anchoring moiety and color-providing moiety, the compound being contained in the photosensitive element as in the first-mentioned embodiment, to split off the insolubilizing or anchoring substituent and thus provide in terms of unexposed areas an imagewise distribution of soluble dye which is free to migrate to another stratum to form a positive color transfer image thereon.

One class of color-providing materials contemplated by this aspect of the invention may be defined as dyes which are insoluble in an aqueous alkaline medium and which may be represented by the formula:

wherein Y' is a dye moiety which is itself soluble and dilfusible in an aqueous alkaline medium; and A is an insolubilizing or immobilizing moiety which when contacted with silver ions is removed from said Y moiety, thereby rendering said Y' moiety diifusible in said aqueous alkaline medium.

The dye moiety Y may comprise any of the general classes of dyes heretofore known in the art which are soluble and diifusible and if necessary, the dye molecule may contain various solubilizing substituents, e.g., sulfonyl, hydroxy or carboxy groups, to improve the solubility characteristics thereof. The anchoring moiety may for example, be an acylic substituent such as a higher alkyl radical, e.g., an alkyl radical containing at least twelve carbon atoms, or a substituent including an aromatic or heterocyclic ring moiety, etc.

Included within the scope of Formula B are dyes which when oxidized by silver ions ring-close to split off the anchor and thereby release the ring closed dye moiety for transfer.

In another aspect of the embodiment of invention wherein a positive transfer image is formed by freeing a dye for migration, use is made of the oxidative properties of silver ions to remove the dye moiety. This type of dye release may be accomplished by cleaving or elimination of the dye moiety, which elimination may also be effected by ring-closure of the compound to split off the dye moiety.

In still another aspect of this embodiment of the invention, dye is rendered mobile and diffusible by a complexing mechanism wherein a silver complex is formed in the dye-containing compound and as a function thereof, a diffusible dye is released or eliminated for transfer. It is also contemplated that a normally immobile dye may be rendered dilfusible by complexing with silver ions to effect positive transfer image formation.

Other mechanisms involving reactions to free a colorproviding material for diffusion in the processing fluid are also contemplated by the present invention.

For example, another system contemplated by the present invention involves the use of silver ions to catalyze or initiate cleavage of an anchor or insolubilizing group to free a color-providing material for transfer. As illustrative of such mechanisms, mention may be made of compounds of the general class:

wherein cleavage between the sulfur and carbonyl moieties removes the higher alkyl insolubilizing group, thus freeing the dye for transfer.

The field of useful color-providing materials may be further extended by the employment of dye substances which are colorless or of a color other than that ultimately desired in a particular environment, e.g., at a particular pH level, but upon change in the environment take on a color change. Dye substances of this type include indicator dyes, leuco dyes, and carbinols of basic dyes. It is also contemplated that dyes may be employed which undergo a color shift or change in spectral absorption characteristics during or after processing. Such dyes may be referred to as temporarily shifted dyes. The temporary shift may, for example, be effected by acylation, the acyl groups being removable by hydrolysis in the alkaline processing composition. As examples of such temporary shifting as applied to dye developers, mention may be made of the inventions described and claimed in applications Ser. No. 789,080 filed Jan. 26, 1959, now abandoned in the name of Howard G. Rogers; Ser. Nos. 418,628 and 418,629 filed Dec. 16, 1964, now U.S. Patents No. 3,307,947 and 3,336,287, respectively in the names of Elbert M. Idelson and Howard G. Rogers; and U.S. Patents No. 3,086,005 and 3,230,085.

While the use of complete dyes has been stated in the foregoing description it will be appreciated that the invention is not limited thereto, and in lieu thereof, one may employ dye intermediates or couplers which are subjected to appropriate reaction prior, during or subsequent to transfer to produce the desired color transfer image.

Positive color images may also be obtained on a sheet material separate from the photosensitive element with compounds such as those described in the first-mentioned embodiment for preparing negative transfer images, e.g., the compounds of Formula A. This may be accomplished by employing a film unit, the processing of which is illustrated in FIG. 2. As shown therein, an exposed silver halide emulsion 12 on a support is processed by spreading between the emulsion layer and a layer of a normally diffusible color-providing material 11 on a support 14 an aqueous alkaline processing composition of the character heretofore described. In exposed areas of emulsion layer 12, silver halide is reduced to image silver, while an imagewise distribution of soluble silver complex is formed in terms of unexposed areas. This imagewise distribution is at least in part transferred by imbibition, to layer 11 where it reacts with the color-providing material to render it non-diffusible in areas corresponding to unexposed areas of emulsion layer 12. This, in turn, produces an imagewise distribution of diffusible color providing material corresponding to exposed areas of the emulsion layer, and removal of this latter imagewise distribution of diffusible color-providing material into the processing composition leaves a positive color image on layer 11. The processing composition employed may be one of the viscous reagents heretofore known in the art which has a greater affinity for emulsion layer 12 than it does for layer 11 so that following processing, layer 11 may be cleanly separated from the processing composition 15 to reveal the positive image.

Any of the dye transfer images prepared in accordance with this invention may be complexed with a suitable metal ion during or after transfer. The metal-complexed dyes may exhibit spectral absorption characteristics appreciably different from the non-complexed dyes. For example, metal complexing may result in a shift of spectral absorption characteristics to provide a dye having a desired color. It is also within the scope of this invention to employ compounds, the non-complexed forms of which are substantially colorless or nondescript, but which, when complexed, are of the desired color.

The complexing may be effected by reacting the dye with a suitable metal-containing compound, e.g., a salt of a zinc, copper, nickel, iron, etc., prior, during or subse quent to image formation to provide the desired metal complex. In a preferred form, complexing is effected subsequent to image formation by swabbing the image with a mixture containing the desired metal.

. The following example illustrates this aspect of the invention.

EXAMPLE IV An orange image prepared in the manner described in Example II was swabbed with an aqueous solution of zinc nitrate. Following swabbing, a magenta negative image was formed.

While in the foregoing description and illustrative examples, reference is made to the preparation of monochromatic images, it will be appreciated that the invention is applicable to the formation of multicolor images. For example, the present invention may be employed in integral multilayer photosensitive elements comprising at least two selectively sensitized photosensitive strata and associated color-providing material, which may be proc essed simultaneously and without separation to provide a multicolor image on a single common image-receiving element.

The expression color as used throughout the foregoing specification and in the appended claims is intended to include the use of a plurality of colors to obtain black.

Since certain changes may be made in the above products and processes without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a diffusion transfer process wherein an exposed silver halide emulsion containing a developable image is developed to obtain from said substance an imagewise distribution of a diifusible color-providing material and said imagewise distribution is transferred, at least in part, by imbibition to a stratum to impart thereto a color transfer image, said color-providing material being a complete dye or a dye intermediate which forms a complete dye during or after transfer; the steps which comprise employing as said color-providing material a complete dye or a dye intermediate reactable with silver ions to provide a differential in mobility or diffusibility in the developing composition between reacted and unreacted material, contacting said exposed silver halide emulsion with an aque ous alkaline processing composition containing a silver halide developing agent and a silver halide solvent to develop said image and to form in terms of undeveloped silver halide an imagewise distribution of a soluble silver complex-providing silver ions for reaction with said material and contacting and thereby reacting said material with said imagewise distribution of said soluble silver complex to form said imagewise distribution of said diffusible color-providing material as a function of said reaction, thereby controlling transfer of said color-providing material to form said color transfer image by said silver ions in said silver complex formed as a function of development of said silver halide emulsion.

2. A process as defined in claim 1 wherein said imagewise distribution of diifusible color-providing material is obtained in terms of unexposed areas of said emulsion and said transfer image is a positive color transfer image.

3. A process as defined in claim 1 wherein said imagewise distribution of difiusible color-providing material is obtained in terms of exposed areas of said emulsion and said transfer image is a negative color transfer image.

4. A process as defined in claim 1 wherein said colorproviding material is a complete dye.

5. A process as defined in claim 1 wherein said substance is a dye which is diffusible in an aqueous alkaline medium and said dye is rendered non-diffusible in said medium by said silver ions, thereby providing an imagewise distribution of dilfusible dye in said medium in terms of exposed areas of said emulsion; and transferring said imagewise distribution of diffusible dye, at least in part, to a dyeable stratum to form a negative color transfer image.

6. A process as defined in claim 5 wherein said dye is a compound of the formula:

wherein A is a substituent reactable with silver ions to provide a reaction product which is non-diffusible in an aqueous alkaline medium; and D is the remainder of the dye molecule.

7. A process as defined in claim 6 wherein said A moiety is the monovalent radical of an organic silver halide antifogging agent selected from the group consisting of benzimidazoles, thiocarbazones, benzotriazoles, mercaptothiazoles, hydroxyquinolines, azolethiones, azopyridines, bis-pyrazoles, and tetrazoindenes.

8. A process as defined in claim 1 wherein said substance is a dye which is non-difiusible in an aqueous alkaline medium and said dye is rendered difiusible in said medium in terms of unexposed areas of said emulsion; and transferring said imagewise distribution of diffusible dye, at least in part, to a dyeable stratum to form a positive color transfer image.

9. A process as defined in claim 8 wherein said dye is a compound of the formula:

wherein Y is a dye moiety which is itself ditfusible in an aqueous alkaline medium; and A is an immobilizing moi ety for rendering said compound non-dilfusible in said medium, said A moiety and Y moiety being separable upon contacting said compound with silver ions, thereby releasing said dye moiety and rendering it diffusible in said medium.

10. A process as defined in claim 1 wherein said silver ions are obtained by applying to said exposed silver halide emulsion a processing composition comprising an aqueous alkaline solution containing a silver halide developing agent and a silver halide solvent, reducing exposed areas of said emulsion to image silver and forming from unexposed silver halide an imagewise distribution of a soluble silver complex containing said silver ions.

11. A process as defined in claim 1 wherein said sub stance and said silver halide emulsion are contained in separate layers in the same element.

12. A process as defined in claim 1 wherein said substance and said silver halide emulsion are contained in the same layer.

13. A process as defined in claim 12 wherein said substance is not normally photographically innocuous and means are provided for rendering said substance effectively innocuous.

14. A process as defined in claim 4 including the step of forming a metal complex of said dye subsequent to image formation.

15. A process as defined in claim 14 wherein said metalcomplexed dye exhibits spectral absorption characteristics materially different from said non-complexed dye.

16. A photographic process for preparing visible images comprising the steps of exposing a light-sensitive silver halide emulsion to form a developable image; contacting said exposed emulsion with an aqueous alkaline processing composition to develop said image and to form an imagewise distribution of a soluble silver complex containing silver ions in terms of unexposed areas of said emulsion; reacting said imagewise distribution of soluble silver complex with a layer containing a member of the group consisting of diifusible color-providing materials which upon reaction with silver ions are rendered nondifiusible, and non-ditfusible color-providing materials which upon reaction with silver ions are rendered diffusible, said color-providing material being a complete dye or a dye intermediate; forming as a function of said reaction an imagewise distribution of diffusible color-providing material; and transferring said imagewise distribution of ditfusible color-providing material to form a color image, thereby controlling transfer of said color-providing material to form said color image by said reaction with said silver ions in said silver complex formed as a function of development of said silver halide emulsion.

17. A photographic process for preparing visible images comprising the steps of exposing a light-sensitive silver halide emulsion to form a developable image; contacting said exposed emulsion with an aqueous alkaline processing composition to develop said image and to form in terms of undeveloped silver halide an imagewise distribution of a soluble silver complex containing silver ions; reacting said imagewise distribution of soluble silver complex with a member of the group consisting of substantially colorless diifusible compounds which, upon reaction with silver ions, are rendered non-diffusible and substantially colorless non-diffusible compounds which, upon reaction With silver ions, are rendered diffusible, said compounds of said group being complexible to provide a color; forming as a function of said reaction an imagewise distribution of a diifusible compound of said group; transferring said imagewise distribution of said diifusible compound by imbibition to a superposed stratum; and reacting said compound with a metal ion to form a metal complex of said compound, said metal complex being colored.

18. A photographic product including a light-sensitive silver halide emulsion layer; a layer containing a member of the group consisting of diffusible color-providing materials which are not themselves silver halide developing agents but which are rendered non-ditfusible upon reaction with silver ions and non-diffusible color-providing materials which are not themselves silver halide developing agents but which are rendered ditfusible upon reaction with silver ions, said color-providing materials being complete dyes or dye intermediates; and means for applying a photographic processing composition comprising an aqueous alkaline solution of a silver halide developing agent and a silver halide solvent in a substantially uniform layer between said emulsion layer and a superposed sheet material.

19. A product as defined in claim 18 wherein said color-providing material is a complete dye; said layer containing said dye is situated in a photosensitive element including also said silver halide emulsion layer; and said sheet material comprises a dyeable stratum.

20. A product as defined in claim 18 wherein said color-providing material is present as a layer on said sheet material.

21. A process as defined in claim 18 wherein said dye is a compound of the formula:

Wherein A is a substituent reactable with silver ions to provide a reaction product which is non-difl'usible in an 14 aqueous alkaline medium; and D is the remainder of the dye molecule.

References Cited UNITED STATES PATENTS 3,196,015 7/1965 Ryan 9629 NORMAN G. TORCHIN, Primary Examiner.

ALFONSO T. SURO-PICO, Assistant Examiner.

US. Cl. X.R. 9629 

